<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        div{
            display: inline-block;
            width: 100px;
            height: 40px;
            border: 1px solid rgb(103, 255, 166);
        }
        .a{
            border-radius: 20px 30px 300px 40px;
        }
        .b{
            height: 50px;
            border-radius: 100px 100px 0 0;}
        .c{
            border-radius: 100px/40px;
        }
    </style>
</head>
<body>
<div class="a"></div>
<div class="b"></div>
<div class="c"></div>
</body>
</html>